The development and manufacture of mechanical parking brakes, which are operated by a person by means of a brake lever pivotably supported about a lever pivot axis, include inter alia the necessary testing of proper operation in relation to the vehicle. In particular, with tests of this type, meeting legal or regulatory requirements may be tested, which requirements, for example, may specify maximum operating forces to be applied to the brake lever necessary to achieve clamping force of the parking brake adequate to hold the vehicle securely on defined gradients or slopes.
To test said parking brake function, it is necessary to measure the actuation force applied to the brake lever by a person when operating the parking brake, for example by means of a force sensor. In this case, however, it has been shown that the actuation force applied by the person to the brake lever can be significantly influenced by several factors, including a) the person operating the brake lever, b) a geometrical arrangement determined by a certain application of the force sensor to the brake lever or the relative position thereof to the brake lever, c) the direction of action of the actuation force applied by the person to the brake lever, and d) their experience regarding the performance of the test method. Said factors have been found to result in measurement results regarding the actuation force applied to the brake lever by the person that are subject to large fluctuations, so that said measurement results may provide relatively imprecise evidence about the actuation force to be actually applied to the brake lever for an adequate clamping or braking effect of the parking brake that is brought about thereby. Therefore, such measurement methods may provide inadequate assessments when using conventional measurement system analyses to assess the measurement quality of a measurement method or system, in particular regarding the repeatability and reproducibility thereof.
There is therefore a need for a force measurement method and a force measurement device for a mechanical parking brake that simply, reliably and accurately measures or determines the actuation force applied to a brake lever when the parking brake is operated by a person, in order to achieve a significant improvement in both the repeatability and the reproducibility. In particular, the method and the device should also be able to be simply applied within a vehicle, i.e. with the parking brake already properly installed, thus the device should be made compact and manageable and so as to be fitted to an existing brake lever of the parking brake without high cost.